1. Field of the Invention
The present invention relates to a zero insertion force (ZIF) electrical connector, and particularly to a ZIF electrical connector for electrically connecting an electronic package such as a central processing unit (CPU) with a circuit substrate such as a printed circuit board (PCB).
2. Description of the Prior Art
Zero insertion force (ZIF) electrical connectors are well known in the computer industry and used for electrically connecting electronic packages such as central processing units (CPUs) with circuit substrates such as printed circuit boards (PCBs). Pertinent examples of such connectors are disclosed in U.S. Pat. Nos. 6,544,065, 6,533,597, 6,508,659, 6,482,022, 6,406,317 and 6,280,223.
Normally, a conventional ZIF electrical connector comprises an insulative base mounted on a PCB, a cover movably mounted on the base, and an actuation member. The base defines a multiplicity of vertical passageways therethrough, and a T-shaped recess in a front end thereof. The passageways receive a corresponding number of electrical contacts therein respectively, and each passageway has a receiving space adjacent a corresponding contact. A hook is formed on the base adjacent to the recess. The cover defines a multiplicity of passages therethrough. The actuation member is accommodated in the recess, and comprises a driving shaft arranged between the base and the cover, and an operating lever extending perpendicularly from an end of the driving shaft. The operating lever can be operated between a first position and a second position, thereby the driving shaft moving the cover with respect to the base. When the operating lever is located at the first position, the passages of the cover are disposed over corresponding receiving spaces of the base, and pins of a CPU can plug through the passages of the cover into the receiving spaces of the base with ZIF. The operating lever is then rotated to the second position, and the hook catches an end portion of the operating lever. The cover pushes the pins of the CPU into corresponding contacts, thereby the connector electrically connecting the CPU with the PCB. Conversely, when the operating lever is rotated to the first position, the CPU can be detached from the connector with ZIF.
In the above-described connector, the operating lever is usually rotated to the first position by means of manual operation. If a force of rotating the operating lever is insufficient, the operating lever is driven only part of the way toward the first position. When the CPU is then attached/detached onto/from the connector, the pins of the CPU interfere with the contacts. The pins and the contacts are thus liable to sustain damage. As a result, the electrical connection between the CPU and the PCB is disrupted or may even fail altogether.
Therefore, it is a need for reliable rotating the operating lever to the first position. To this end, a spring is assembled onto the operating lever to automatically drive the operating lever to rotate to the first position. The spring has a first end attached to the base in the recess, and a second end fastened on the operating lever. When the operating lever is located the second position, the second end of the coil spring is rotated under forces from the operating lever, with the spring undergoing steadily increasing tension during such rotation. Accordingly, the operating lever can automatically rotate to the first position, as soon as being released from the hook, and not in any intermediate position. In this state, the pins of the CPU can reliably insert/remove into/from the passageways with ZIF. However, in use of the connector, the operating lever is oriented at the second position at all time. The spring undergoes the tension, and the operating lever stands contrary force from the spring. At the same time, the hook endures compression from the operating lever. Generally, the hook is made of insulative material such as plastic. Thus, the hook is liable to be broken when the hook bears the force for a long time. When this happens, the operating lever automatically rotates to the first position. Electrical connection between the CPU and the PCB is disrupted.
In view of the above, a new ZIF electrical connector that overcomes the above-mentioned disadvantages is desired.